We have been studying the slope monitoring method using digital vision metrology. This study developed a technique for measuring the deformation of a slope using this measurement without setting any fiducial points and with the method of simply obtaining initial approximations of coordinate values from the images taken. This measurement method has the advantage of obtaining the three coordinates of many measurement points at cheap cost. In this paper, the precision of the measurement values obtained by the proposed technology is verified in the actual rock slope and we discuss its feasibility based on the experimental results of application of the measurement values to the design of countermeasure construction.

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To evaluate the water retentivity effects of cover with Sasa Sasa nipponica Makino et Shibata) on the surface layer of slope, the field observation was conducted to measure the soil suction in the surface layer at the sites of slopes with and without Sasa cover during raining. Also, the physical properties for soil of surface layer were measured in the laboratory. When rainfall was observed with the precipitation of 30mm, 10-15% of precipitation was retained in the layer of volcanic sand. And 70% of precipitation infiltrated into the deeper. On the other hand, 70% of that was retained in the Sasa mat (rhizome distributing soil layer), in which the rhizome was stretched around, on the slope covered with it, while 7-15% of that was in the lower volcanic sand. Moreover, the side outflow and the deeper infiltration were slight. Based on these findings, once Sasa mat is formed, the slope has more water retaintivity. Therefore, it plays a role to lighten the burden of rainfall, so that Sasa mat is expected to prevent disasters such as erosion, surface failure and so on.

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Featuring excellent fireproof and insulating properties, plasterboard has a versatile application as economical basic construction materials. Annual production amount of plasterboard is approximately 5 million tons. During the three stages of production, construction and dismantlement, approximately 1.5 million tons of waste plasterboard are generated each year. Shortage of waste disposal landfill is also an increasing problem in recent years. We have developed a technology for bassanite production obtained from waste plasterboard to promote waste plasterboard recycling. This system can produce large volumes of high quality bassanite in a short time. Bassanite is produced by heating gypsum obtained from waste plasterboard, under conditions of 130°C or more. It is also environmentally friendly, due to its neutral nature. In addition, we examined the development of a technology for recycling waste plasterboard as a soil improvement material. The effects of bassanite content on stress-strain behavior of cement-stabilized soils are quantified. The unconfined compressive strength increases with increasing bassanite content. This is due to concomitant decrease in the water content and increase in the dry density. We also found that bassanite is especially effective for soils with high water content. These properties make bassanite obtained from waste plasterboard useful as an improver for soft soils.

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In this paper, the effects of the fundamental parameters such as water content in soil, cooling pipe and initial soil temperatures on the freezing rate in soil were investigated experimentally. The freezing rate was calculated from the time variation of radial temperatures in soil apart from the cooling pipe. As a result, it was found that the freezing rate was influenced considerably by the initial water content in soil. Furthermore, a new cooling method using two-steps cooling was proposed to economize on electric power, that will cut down on expenses.

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Coal ash is sometimes used to reclaim seashore and forms soft ground because of its high fines content and high water content. So far, soil improvement methods for cohesive soils have been employed in improving coal ash reclaimed ground. In this research, the dynamic compaction method, which was originally developed for non-cohesive soils, is applied to a coal ash reclaimed site for the first time. A series of in situ soil tests, composed of cone penetration tests before and after the improvement, in situ pore pressure measurement, etc. is carried out to evaluate the improvement effect. Consequently, it can be said that dynamic compaction method effectively improves coal ash ground. Furthermore an evaluation method for mechanical properties of improved coal ash ground is proposed based on the measured results in this site.

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Uniaxial tension test and Brazilian (splitting tension) test were carried out on Inada granite in R, G and H directions, i.e., the directions perpendicular to rift, grain and hardway planes respectively. Comparison of the tensile strengths obtained by the tests showed that the strength by the Brazilian test was slightly higher than that by the uniaxial tension test. The difference between them, however, was small and less than standard deviation of the strength by the Brazilian test. Additionally, scatter of the strength by the Brazilian test was more than that by the uniaxial tension test. Regarding to anisotropy of Inada granite, it was recognized according to the results of both tests that the tensile strength in R direction was obviously lower than those in the other two directions.

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